U.S. patent application number 12/296376 was filed with the patent office on 2009-12-10 for plasma display panel and method for manufacturing the same.
Invention is credited to Akihiro Fujimoto, Taiki Makino, Koji Ohira, Masahiro Sawa.
Application Number | 20090302763 12/296376 |
Document ID | / |
Family ID | 38778229 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090302763 |
Kind Code |
A1 |
Makino; Taiki ; et
al. |
December 10, 2009 |
PLASMA DISPLAY PANEL AND METHOD FOR MANUFACTURING THE SAME
Abstract
In a plasma display panel wherein lattice-like ribs are formed,
an impurity gas inside the panel is easily exhausted. The panel has
a paired substrates facing each other. The peripheral portions of
the panel are bonded to each other to be sealed. The panel is
manufactured by allowing an impurity gas located between the
substrates to be exhausted upon carrying out the sealing/bonding
process. The panel includes a cell-defining rib and a dummy rib.
The cell-defining rib has longitudinal ribs and lateral ribs, which
is formed in a display area between the paired substrates. The
dummy rib has the same shape as that of the cell-defining rib,
which is formed in a non-display area which covers from an outer
edge of the display area over to the periphery of the substrates, a
ventilation passage being formed in the non-display area in which
the dummy rib is formed.
Inventors: |
Makino; Taiki; (Miyazaki,
JP) ; Sawa; Masahiro; (Miyazaki, JP) ; Ohira;
Koji; (Miyazaki, JP) ; Fujimoto; Akihiro;
(Miyazaki, JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700, 1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Family ID: |
38778229 |
Appl. No.: |
12/296376 |
Filed: |
May 31, 2006 |
PCT Filed: |
May 31, 2006 |
PCT NO: |
PCT/JP2006/310915 |
371 Date: |
February 2, 2009 |
Current U.S.
Class: |
313/582 ;
445/25 |
Current CPC
Class: |
H01J 11/36 20130101;
H01J 2211/368 20130101; H01J 9/385 20130101; H01J 11/54 20130101;
H01J 11/12 20130101 |
Class at
Publication: |
313/582 ;
445/25 |
International
Class: |
H01J 17/49 20060101
H01J017/49; H01J 11/02 20060101 H01J011/02 |
Claims
1. A plasma display panel, which has a paired substrates facing
each other, the peripheral portions of which are bonded to each
other to be sealed, and is manufactured by allowing an impurity gas
located between the substrates to be exhausted upon carrying out
the sealing/bonding process, the plasma display panel comprising: a
cell-defining rib having longitudinal ribs and lateral ribs, which
is formed in a display area between the paired substrates; and a
dummy rib having the same shape as that of the cell-defining rib,
which is formed in a non-display area which covers from an outer
edge of the display area over to the periphery of the substrates, a
ventilation passage being formed in the non-display area in which
the dummy rib is formed.
2. The plasma display panel according to claim 1, wherein the
ventilation passage is made of a plurality of ventilation passages,
and the non-display area in which the dummy rib is formed is
divided into a plurality of island shapes by a plurality of these
ventilation passages.
3. The plasma display panel according to claim 2, wherein each
dummy rib located on each of corners of areas divided into the
island shapes has a corner portion which is formed into a round
shape.
4. The plasma display panel according to claim 2, wherein the
ventilation passage is provided on a border portion between the
display area and the non-display area, with each rib, located on
each of corners of the display area, having a corner portion which
is formed into a round shape.
5. The plasma display panel according to claim 4, wherein a rib
located on the outer edge of the display area has a width of at
least each corner portion which is wider than a width of a rib
which is not located on the outer edge.
6. The plasma display panel according to any one of claims 1 to 5,
wherein the ventilation passage is formed in a manner so as to
avoid a temporarily securing area in which, when the paired
substrates are aligned face to face with each other and the
peripheral portions are bonded and sealed with each other, the
paired substrates are sandwiched by a clip.
7. A method for manufacturing a plasma display panel comprising the
steps of: forming a ventilation passage on a non-display area in
which a dummy rib has been formed upon forming a cell-defining rib
having longitudinal ribs and lateral ribs on a display area of one
of substrates, as well as forming the dummy rib having the same
shape as that of the cell-defining rib on the non-display area
which covers from an outer edge of the display area over to a
peripheral portion of the substrate; then allowing one of
substrates to be made face to face with other substrate and
carrying out a sealing/bonding process on peripheral portions
thereof; and exhausting an impurity gas from a gap between the two
substrates upon carrying out the sealing/bonding process.
Description
TECHNICAL FIELD
[0001] This invention relates to a plasma display panel
(hereinafter, referred to as a "PDP") and a method for
manufacturing the same, and specifically relates to a PDP in which
a frontside substrate and a backside substrate are aligned face to
face with each other and peripheral portions are bonded to each
other to be sealed with a sealing/bonding material, and a method
for manufacturing the same.
BACKGROUND ART
[0002] A three-electrode surface-discharge-type PDP of an AC-drive
type has been known as a conventional PDP. This PDP is manufactured
through processes in which the frontside substrate on which desired
constituent elements, such as electrodes, a dielectric layer, a
phosphor layer and ribs (barrier ribs), are formed and the backside
substrate are aligned face to face with each other and the
peripheral portions are bonded to each other to be sealed. This
process for bonding the peripheral portions to each other to be
sealed is referred to as a sealing process, a sealing/bonding
process, a sealing/bonding/exhausting process and the like, and in
the present specification, it is referred to as the sealing/bonding
process.
[0003] In this sealing/bonding process, normally, a glass
sealing/bonding material is applied to the peripheral portion of
the backside substrate, and the frontside substrate is superposed
on the backside substrate, with the peripheral portions of two
substrates being sandwiched by clips to be temporarily secured, and
the two substrates in this state are subjected to a heating process
so that the two substrates are air-tightly bonded to each other. In
this heating process, while the glass sealing/bonding material is
heated to be fused, a negative pressure is applied to an inside of
the PDP so that an impurity gas is exhausted from the inside of the
PDP, and a discharge space inside the PDP is successively filled
with a discharge gas.
[0004] The temporarily securing process by the clips is carried out
by sandwiching the peripheral portions of the substrates with the
clips at a plurality of positions (for example, four positions).
For this reason, dummy ribs are formed up to a clip-sandwiching
area on the periphery of the substrates so that the frontside
substrate and the backside substrate are bonded to each other to be
sealed, with a predetermined gap.
[0005] On the other hand, examples of a rib structure of the PDP
include such as a linear structure (stripe rib structure) in which
a plurality of ribs are provided in a longitudinal direction
(column direction of display) so that the discharge space is
divided only in a lateral direction (row direction of display) and
a lattice-like structure (a box rib structure and a waffle rib
structure) in which the discharge space is divided for each cell by
providing ribs in the lateral direction and the longitudinal
direction. In recent years, there have been strong demands for PDPs
having the box rib structure so as to achieve high precision in
pixels.
DISCLOSURE OF THE INVENTION
Problems to Be Solved by the Invention
[0006] However, since the PDP of the box rib structure is a
closed-type rib structure, a ventilation conductance inside the
panel is small, in comparison with a PDP of the stripe rib
structure, resulting in a problem in which an exhausting process of
the impurity gas becomes difficult. When a removal of the impurity
gas is insufficient, panel performances deteriorate. More
specifically, a reduction in luminance and voltage fluctuations
occur due to degradation of phosphors, and panel display
irregularities tend to occur.
[0007] Therefore, various structures have been proposed so as to
improve a ventilation passage inside the panel. For example, a
structure in which a groove is provided in a non-display area (see
Patent Document 1) has been known as an attempt to enlarge the
ventilation passage in the non-display area. Moreover, another
structure has been known in which an attempt is made to improve an
exhaust efficiency by providing more ventilation passages on a
longer side of the panel than those on a shorter side thereof (see
Patent Document 2). [0008] Patent Document 1: JP-A No. 11-238466
[0009] Patent Document 2: JP-A No. 2003-217457
[0010] In view of the above state of the art, the present invention
has been devised, and its object is to improve the exhaust process
inside the panel in the PDP of the closed-type rib structure by
forming the ventilation passage in the non-display area.
Means to Solve the Problems
[0011] The present invention provides a plasma display panel, which
has a paired substrates facing each other, the peripheral portions
of which are bonded to each other to be sealed, and is manufactured
by allowing an impurity gas located between the substrates to be
exhausted upon carrying out the sealing/bonding process, the plasma
display panel comprising: a cell-defining rib having longitudinal
ribs and lateral ribs, which is formed in a display area between
the paired substrates; and a dummy rib having the same shape as
that of the cell-defining rib, which is formed in a non-display
area which covers from an outer edge of the display area over to
the periphery of the substrates, a ventilation passage being formed
in the non-display area in which the dummy rib is formed.
Effects of the Invention
[0012] In accordance with the present invention, the ventilation
passage is formed in the non-display area in which the dummy rib is
formed; therefore, when the paired substrates are aligned face to
face with each other and the peripheral portions are bonded and
sealed with each other in a PDP with closed-type ribs formed
between the substrates, an exhausting operation of the impurity gas
existing between the substrates can be desirably carried out so
that it is possible to provide a high-quality PDP with high
reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1(a) and 1(b) are explanatory drawings which show a
structure of a PDP in accordance with the present invention.
[0014] FIGS. 2(a) and 2(b) are partially exploded perspective views
which show the PDP of the present invention in detail.
[0015] FIG. 3 is an explanatory drawing which shows a structure of
embodiment 1 of the present invention.
[0016] FIG. 4 shows a comparative example of a PDP in which no
ventilation passage is formed.
[0017] FIG. 5 is an explanatory drawing which shows a structure of
embodiment 2 of the present invention.
[0018] FIG. 6 is an explanatory drawing which shows a structure of
embodiment 3 of the present invention.
[0019] FIG. 7 is an explanatory drawing which shows a structure of
embodiment 4 of the present invention.
[0020] FIG. 8 is a plan view which shows a box rib placed on a
corner of a display area in the PDP of the present invention.
[0021] FIG. 9 is a plan view which shows a box rib placed on a
corner of a display area in the PDP of the present invention.
REFERENCE NUMERALS
[0022] 10 PDP [0023] 11 Frontside substrate [0024] 12 Transparent
electrode [0025] 13 Bus electrode [0026] 17, 24 Dielectric layer
[0027] 18 Protective film [0028] 21 Backside substrate [0029] 28R,
28G, 28B Phosphor layer [0030] 29 Box rib [0031] 29a Corner portion
of box rib [0032] 29b Outer edge box rib [0033] 30 Discharge space
[0034] 31 Display area [0035] 32 Non-display area [0036] 33 Dummy
rib [0037] 34 Clip sandwiching area [0038] 41 Glass sealing/bonding
material [0039] 42 Ventilation hole [0040] 43 Ventilation passage
[0041] A Address electrode [0042] L Display line [0043] X,Y Display
electrode
BEST MODE FOR CARRYING OUT THE INVENTION
[0044] In the present invention, examples of the paired substrates
include a substrate made of glass, quartz or ceramics and a
substrate prepared by forming desired constituent elements, such as
an electrode, an insulating film, a dielectric layer and a
protective film, on such substrate.
[0045] The electrodes may be formed by using various materials and
methods conventionally known in the art. Examples of materials used
for these electrodes include transparent conductive materials, such
as ITO and SnO.sub.2, and metal conductive materials, such as Ag,
Au, Al, Cu and Cr. Various methods conventionally known in the art
can be used for forming the electrodes. For example, a
thick-film-forming technique such as a printing may be used for
forming the electrodes, or a thin-film-forming technique, such as a
physical deposition method and a chemical deposition method, may be
used for forming them. Examples of the thick-film-forming technique
include a screen printing method and the like. In the
thin-film-forming technique, examples of the physical deposition
method include such as a vapor deposition method and a sputtering
method. Examples of the chemical deposition method include such as
a thermal CVD method, a photo CVD method, or a plasma CVD
method.
[0046] In the present invention, the cell-defining rib may be
formed by the longitudinal rib and the lateral rib. The
longitudinal rib and the lateral rib are not necessarily required
to be made orthogonal to each other, and may be prepared so as to
intersect with each other with any angle. Heights of the
longitudinal rib and the lateral rib are not necessarily required
to be identical, and may be made different from each other.
[0047] The ventilation passage may be provided in the non-display
area in which the dummy rib is formed. This ventilation passage may
be prepared by forming no rib at a position to form the ventilation
passage. The ventilation passage may have a linear-shape or a
curved shape.
[0048] In the above structure, the ventilation passage may be
formed by a plurality of ventilation passages, and the non-display
area having the dummy rib formed therein may be divided into a
plurality of island states by a plurality of these ventilation
passages. In this case, an edge portion of a dummy rib, located at
a corner of each area divided into the island state, is desirably
formed with a round shape.
[0049] The ventilation passage is provided at a border portion
between the display area and the non-display area, and an edge
portion of a rib located at a corner of the display area may be
formed with a round shape. Moreover, a rib to be positioned at an
outer edge of the display area is desirably designed to have at
least a width of the corner portion which is made wider than the
width of a rib which is not positioned at the outer edge.
[0050] The ventilation passage is desirably formed so as to avoid a
temporarily securing area in which the paired substrates are
sandwiched by the clips upon aligning the paired substrates to be
made face to face with each other and bonding the peripheral
portion to be sealed.
[0051] Moreover, the present invention relates to a method for
manufacturing the plasma display panel which includes processes in
which the cell-defining rib, made of the longitudinal rib and the
lateral rib, is formed on the display area of one of the
substrates, and, upon forming the dummy rib having the same shape
as that of the cell-defining rib in the non-display area which
covers from the outer edge of the display area over to the
peripheral portion of the substrate, the ventilation passage is
formed in the non-display area in which the dummy rib has been
formed, and then, one of the substrates is made face to face with
the other substrate with its peripheral portions being bonded to be
sealed, and upon carrying out the sealing/bonding process, the
impurity gas is discharged from a gap between the two
substrates.
[0052] Referring to Figs., the present invention will be described
in detail by means of embodiments, hereinafter. Here, the present
invention is not intended to be limited by these, and various
modifications may be made therein.
[0053] FIGS. 1(a) and 1(b) are explanatory drawings which show a
structure of the PDP of the present invention. FIG. 1(a) is a
general view, and FIG. 1(b) is a partially exploded perspective
view. This PDP is a three-electrode surface-discharge-type PDP of
an AC-drive type for a color display.
[0054] A PDP 10 is configured by a front side substrate 11 on which
constituent elements having functions as the PDP are formed, and a
backside substrate 21. As the frontside substrate 11 and the
backside substrate 21, for example, a glass substrate is used;
however, in addition to the glass substrate, a quartz substrate, a
ceramic substrate or the like may be used.
[0055] On an inner side face of the front substrate 11, display
electrodes X and display electrodes Y are disposed with equal
intervals in a horizontal direction. All gaps between the adjacent
display electrodes X and display electrodes Y form display lines L.
Each of the display electrodes X and Y is configured by a
transparent electrode 12 having a wide width, made of ITO,
SnO.sub.2 or the like, and a bus electrode 13 having a narrow
width, made of metal, for example, Ag, Au, Al, Cu, and Cr, as well
as a laminated body (for example, Cr/Cu/Cr laminated structure)
thereof or the like. Upon forming these display electrodes X and Y,
the thick-film-forming technique such as the screen-printing
process is used for Ag and Au, and the thin-film-forming technique,
such as the vapor deposition method and the sputtering method, and
an etching technique are used for the other materials so that a
desired number of electrodes having a desired thickness, width and
gap can be formed.
[0056] Here, in the present PDP, a PDP having a so-called ALIS
structure in which the display electrodes X and the display
electrodes Y are placed with equal intervals, with each gap between
the adjacent display electrode X and display electrode Y being
allowed to form the display line L, has been exemplified; however,
the present invention may also be applied to a PDP having a
structure in which paired display electrodes X and Y are placed
separately with a distance (non-discharge gap) in which no
discharge is generated.
[0057] On the display electrodes X and Y, a dielectric layer 17 is
formed in a manner so as to cover the display electrodes X and Y.
The dielectric layer 17 is formed by processes in which a glass
paste, made from a glass flit, a binder resin and a solvent, is
applied onto the frontside substrate 11 by using the
screen-printing method and fired thereon. The dielectric layer 17
may be formed by forming a SiO.sub.2 film using the plasma CVD
method.
[0058] A protective film 18, used for protecting the dielectric
layer 17 from damage due to collision of ions generated by
discharge upon displaying, is formed on the dielectric layer 17.
This protective film is made from MgO. The protective film may be
formed by using the known thin-film forming process in the art,
such as an electron beam vapor deposition method and the sputtering
method.
[0059] On the inner side face of the backside substrate 21, a
plurality of address electrodes A are formed in a direction
intersecting with the display electrodes X and Y on a plan view,
and a dielectric layer 24 is formed in a manner so as to cover the
address electrodes A. The address electrodes A generate an address
discharge used for selecting cells to emit light at intersections
with the display electrodes Y, and each of them is formed into a
three-layer structure of Cr/Cu/Cr. These address electrodes A may
also be formed by using another material, such as Ag, Au, Al, Cu
and Cr. In the same manner as in the display electrodes X and Y,
upon forming these address electrodes A, the thick-film-forming
technique such as the screen-printing process is used for Ag and
Au, and the thin-film-forming technique, such as the vapor
deposition method and the sputtering method, and the etching
technique are used for the other materials so that a desired number
of electrodes having desired thickness, width and gap can be
formed. The dielectric layer 24 may be formed by using the same
materials and the same methods as those for the dielectric layer
17.
[0060] Lattice-like ribs 29, used for separating the discharge
space for each cell, are formed on the dielectric layer 24 between
the adjacent address electrodes A. The lattice-like ribs 29 are
also referred to as box ribs, mesh-like ribs, waffle ribs and the
like. The ribs 29 may be formed by using a sand blasting method, a
photo-etching method or the like. For example, in the sand blasting
method, a glass paste, made from a glass frit, a binder resin, a
solvent and the like, is applied onto the dielectric layer 24, and
after the glass paste has been dried, cut particles are blasted
onto a resulting glass paste layer, with a cutting mask having
apertures of a rib pattern being placed thereon, so that the glass
paste layer exposed to the mask apertures is cut, and a resulting
substrate is then fired; thus, the lattice-like ribs 29 are formed.
Moreover, in the photo-etching method, in place of cutting by using
the cut particles, a photosensitive resin is used as the binder
resin, and after exposing and developing processes by the use of a
mask, the resulting substrate is fired so that the lattice-like
ribs 29 are formed.
[0061] On ide faces and a bottom face of a cell having a
rectangular shape on the plan view, surrounded by the lattice-like
ribs 29, phosphor layers 28R, 28G and 28B corresponding to red (R),
green (G) and blue (B) are formed. The phosphor layers 28R, 28G and
28B are formed through processes in which a phosphor paste
containing a phosphor powder, a binder resin and a solvent is
applied onto inside of a cell surrounded by the ribs 29 by using
the screen-printing method or a method using a dispenser, and after
these processes have been repeated for each of the colors, a firing
process is carried out thereon. These phosphor layers 28R, 28G and
28B may also be formed by using a photolithographic technique in
which a sheet-shaped phosphor layer material (so-called green
sheet) containing the phosphor powder, the photosensitive material
and the binder resin is used. In this case, a sheet having a
desired color may be affixed onto an entire face of a display area
on the substrate, and the sheet is subjected to exposing and
developing processes; thus, by repeating these processes for each
of the colors, the phosphor layers having the respective colors are
formed in the corresponding cell.
[0062] The PDP is manufactured through processes in which the
frontside substrate 11 and the backside substrate 21 are aligned
face to face with each other in a manner so as to allow the display
electrodes X, Y and the address electrodes A to intersect with each
other, and a peripheral portion thereof is sealed, with a discharge
space 30 surrounded by the ribs 29 being filled with a discharge
gas formed by mixing Xe and Ne. In this PDP, the discharge space 30
at each of intersections between the display electrodes X, Y and
the address electrodes A forms one cell (unit light-emitting area)
which is a minimum unit of a display. One pixel is configured by
three cells of R, B and G.
[0063] FIGS. 2(a) and 2(b) are partially exploded perspective views
which show the PDP in detail. FIG. 2(a) shows the frontside
substrate, and FIG. 2(b) shows the backside substrate.
[0064] As shown in FIG. 2(b), on the backside substrate 21, a
cell-defining rib 29 made of the longitudinal ribs and the lateral
ribs is formed on a display area 31, and continuously from the
cell-defining rib on the display area, a dummy rib 33 having the
same shape as that of the cell-defining rib is formed on a
non-display area 32 which is placed so as to cover from an outer
edge of the display area 31 over to a peripheral portion of the
substrate.
[0065] The cell-defining lattice-like rib formed on the display
area 31 is referred to as a box rib 29, and a lattice-like rib
formed on the non-display area 32 is referred to as the dummy rib
33.
[0066] The phosphor layers are formed in each of cells on the
display area 31, while no phosphor layers are formed in each of
cells on the non-display area 32. The ventilation passage, which
will be described later, is formed in the non-display area 32 on
which the dummy rib 33 is formed.
[0067] A glass sealing material 41 is applied onto the periphery of
the backside substrate 21. This glass sealing material 41 is
obtained through processes in which the glass paste, made from the
glass frit, the binder resin, and the solvent, is applied thereto,
and dried thereon, and this is then temporally fired so that the
binder resin component is burned to disappear.
[0068] FIG. 3 is an explanatory drawing which shows a structural
state on the plan view of the PDP of embodiment 1.
[0069] As described earlier, the PDP 10 is manufactured through
processes in which the frontside substrate 11 on which the display
electrodes, the dielectric layer and the protective film are formed
and the backside substrate 21 on which the address electrodes, the
dielectric layer, the lattice-like rib and the phosphor layers are
formed are aligned face to face with each other, and the peripheral
portion of the substrates is sealed with the glass sealing material
41, with the discharge space surrounded by the ribs being filled
with the discharge gas formed by mixing Xe and Ne. The box rib is
formed on the display area 31 of the backside substrate 21, and the
dummy rib is formed on the non-display area 32.
[0070] Here, on the non-display area 32 where the dummy rib has
been formed, linear ventilation passage 43, each having a width of
L, are formed on right and left sides of the substrate in the
longitudinal direction. This ventilation passage 43 is formed
described below.
[0071] The box rib and the dummy rib are formed by using the sand
blasting method. In this sand blasting method, the glass paste,
made from the glass frit, the binder resin, the solvent and the
like, is applied onto the substrate, and after the glass paste has
been dried thereon, cut particles are blasted onto the resulting
glass paste layer, with the cutting mask having apertures of the
rib pattern being placed thereon, so that the glass paste layer
exposed to the mask apertures is cut, and the resulting substrate
is then fired; thus, the box rib and the dummy rib are formed. In
this case, the cutting mask is formed by processes in which, after
a photosensitive dry film resist has been laminated on the
substrate, this is exposed through a photo-mask, and then
developed, and the ventilation passage 43 may be formed by
preparing the shape of the photo-mask at this time as a shape with
ventilation passage. When the ribs are formed by using the
photo-etching method, the ventilation passage is also formed by
preparing the shape of the photo-mask as a shape with ventilation
passage.
[0072] In the sealing/bonding process for sealing/bonding the
peripheral portions of the frontside substrate 11 and the backside
substrate 21, after the glass sealing material 41 has been applied
to the periphery of the backside substrate 21, and then temporarily
fired thereon, the frontside substrate 11 is made to face the
backside substrate 21, and the two substrates are sandwiched by the
clips (not shown) made of metal, and temporarily secured to each
other, and in this state, a heating process is carried out thereon
so that the two substrates are air-tightly bonded to each other. In
this heating process, while the glass sealing material 41 is being
heated to be fused, air is drawn through a ventilation hole 42
formed in the backside substrate 21 to apply a negative pressure to
the inside of the PDP so that the impurity gas is exhausted from
the inside of the PDP, and the discharge space inside the PDP is
successively filled with the discharge gas. At this time, a gap
between the non-display area 32 and the glass sealing material 41
and the ventilation passages 43 serve as ventilation (exhaust)
paths.
[0073] The above temporarily securing process by the clips is
carried out by sandwiching clip-sandwiching areas (temporarily
securing areas) 34 formed on four portions of the periphery of the
substrates with clips. Therefore, the dummy ribs are formed up to
the clip-sandwiching areas 34 so that the frontside substrate 11
and the backside substrate 21 are not curved by the sandwiching
clips, and sealed and bonded to each other with a predetermined
gap.
[0074] In the present embodiment, the clip-sandwiching areas 34 are
prepared at four portions on the right and left sides of the
panels; however, positions, number and size of the clip-sandwiching
areas 34 are not particularly limited. However, in order to
maintain balance relative to a panel strength, clip positions are
desirably disposed with equal intervals.
[0075] In the present embodiment, the box ribs and the dummy ribs
are separated from each other on each short side of the substrate,
and this separated portion is formed into the ventilation passage
43 having a width L so as to be utilized as the ventilation path.
Therefore, the dummy ribs are separated by the ventilation passage
43 into an island state. As described above, the dummy rib with its
periphery completely separated from other ribs is referred to as an
island-state dummy rib.
[0076] FIG. 4, which shows a comparative example, is an explanatory
drawing which shows a state on the plan view of a PDP having no
ventilation passage formed therein. As shown in this Fig., when no
ventilation passage is formed in the non-display area 32, the
ventilation path to be used in the sealing/bonding process is only
given by the gap between the non-display area 32 and the glass
sealing material 41.
[0077] In contrast, in the above embodiment, since the ventilation
passage is formed, the exhausting operation of the impurity gas and
a filling operation of the discharge gas can be sufficiently
carried out. Moreover, the dummy rubs at the clip positions are
virtually the same as those of the comparative example, the panel
strength which is virtually the same as strength of the comparative
example can be obtained.
[0078] In this manner, the ventilation passage which penetrates the
non-display area is formed within the non-display area in which the
dummy ribs are formed, with a temporarily securing area for the
clips being maintained, and this ventilation passage is maintained
as the ventilation path. With this arrangement, while the
substrates are sandwiched by the clips in the same manner as in a
conventional structure, the exhausting operation of the impurity
gas and the filling operation of the discharge gas in the
sealing/bonding process can be preferably carried out so that it
becomes possible to improve a quality of the PDP.
[0079] FIG. 5 is an explanatory drawing which shows a structural
state on the plan view of a PDP of embodiment 2.
[0080] This embodiment differs from embodiment 1 in which right and
left island-state dummy ribs are divided into a plurality of
island-state dummy ribs. With this arrangement, a plurality of
ventilation passages are formed among the dummy ribs, and a
plurality of these ventilation passages can be utilized as
ventilation paths. When the width of each ventilation path is made
too wide, the panel strength against an external pressure is
lowered; however, by using a plurality of the island-state dummy
ribs thus separated in the present embodiment, the ventilation path
can be widened without a reduction in the panel strength against
the external pressure.
[0081] Also in this case, the ventilation passage is not placed
within the clip-sandwiching area. However, so as not to cause
deviations in a ventilation conductance inside the panel, the
island-state dummy ribs are preferably placed with equal intervals
based upon the clip-sandwiching area.
[0082] FIG. 6 is an explanatory drawing which shows a structural
state on the plan view of a PDP of embodiment 3.
[0083] This embodiment differs from embodiment 2 in which an
R-shape is provided on each of the corner portions of the dummy rib
positioned on each of the corners of island-state dummy ribs
divided into a plurality of portions, so as to form a round
shape.
[0084] The reason for this structure is described as follows: that
is, upon forming the box ribs and the dummy ribs, when these are
formed by using sand blasting, a side cut tends to occur in the rib
at the end portion of the rib in a nozzle shifting direction of the
cutting mask, upon shifting a nozzle used for blasting cutting
particles.
[0085] Consequently, upon firing the ribs in a succeeding firing
process, this side-cut portion tends to protrude upward. When the
rib end portion protrudes upward, upon aligning the backside
substrate and the frontside substrate face to face with each other,
the frontside substrate is warped due to this protruding portion,
and this warped frontside substrate vibrates due to influences of
driving pulses upon application of a voltage to the electrodes,
with a result that these vibrations enter an audible region to
occasionally cause an abnormal noise.
[0086] Therefore, in order to prevent this upward protrusion, the
R-shape is formed on each of the corner portions of the dummy rib
positioned on the corner of each island-state dummy rib so that the
corner portion is formed into the round shape. In this case, by
taking this upward protrusion into consideration, the height of the
dummy ribs may be preliminarily designed to be slightly lower, upon
forming the ribs.
[0087] FIG. 7 is an explanatory drawing which shows a structural
state on the plan view of a PDP of embodiment 4.
[0088] This embodiment differs from embodiment 3 in which
ventilation passages are formed on four sides of the periphery of
the display area. That is, the ventilation passages are provided on
all the border portions between the display area and the
non-display area, and an R-shape is formed on each of the corner
portions of the box rib positioned on each of the corners of the
display area so as to form a round shape.
[0089] The reason for this shape, which is the same as the above
reason, is to prevent the end portion of the rib from protruding
upward. However, when ventilation passages are formed on the four
sides of the display area, the box ribs on the display area might
collapse to impair the display cells on the end portions of the
display area. FIGS. 8 and 9 show solutions to this problem.
[0090] FIGS. 8 and 9 are plan views which shows box ribs located on
the corners of the display area in the PDP of the present
invention. FIG. 8 shows an example in which a width of a corner rib
is made wider, and FIG. 9 shows an example in which a width of a
peripheral rib is made wider.
[0091] In a first solution, as shown in FIG. 8, the width of the
corner portion 29a of the box rib located on each of the corners of
the display area is made wider than the width of the other box ribs
29. With this structure, the corner portion 29a of the box rib is
formed into the R-shape without impairing the display cells. In
order to further reduce an amount of upward protrusion, the greater
the radius of R, the better. However, in order to prevent
deviations in the amount of upward protrusion from becoming larger,
an attempt is made so as not to make the rib too wide.
[0092] In a second solution, as shown in FIG. 9, the width of the
outer edge box ribs 29b located on the outer edge of the display
area is made wider than the width of the box ribs 29 which are not
positioned on the outer edge. When the width of the outer-edge box
ribs 29b is made wider, the ventilation path is slightly narrowed;
however, the R-shape of the corner portion can be made larger.
[0093] In this manner, by providing the ventilation path in the
non-display area in which dummy ribs are formed, it is possible to
ensure the ventilation path to be used upon carrying out the
sealing/bonding process on the substrates so that the exhausting
operation of the impurity gas and the filling operation of the
discharge gas can be sufficiently carried out. Moreover, since the
ventilation path between the dummy ribs and the glass sealing
material is made narrower by providing the ventilation passage in
the non-display area, and as a result, it becomes possible to make
the outer shape of the panel smaller.
[0094] As described above, in accordance with the present
embodiments, the exhausting operation of the inside of the panel
and the filling operation of the discharge gas into the panel can
be preferably carried out in the PDP having the closed-type rib
structure by forming the ventilation passage in the non-display
area with the temporarily securing area by clips being maintained,
so that it becomes possible to improve the quality of the PDP.
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